1. Field of the Invention
This invention relates to a car body work sub-frame mounting structure.
2. Description of the Related Art
A technology, which mounts a sub-frame between side members which are longitudinally disposed on both sides of a car body work and secures suspensions to the sub-frame, is disclosed in for example Japanese Unexamined Utility Model Publication No. 5-62383. The above technology relates to a suspension member securing structure; and disposes side frames longitudinally on both sides of a car body work and protrudes vertical two-staged box-shaped brackets from the bottom faces of the side frames as illustrated in FIG. 2. Then, a cylindrical nut member is vertically inserted through the brackets, and a suspension member (corresponding to the sub-frame) is secured to the cylindrical nut member with a bolt.
In the above technology, a distance between the side frames is determined according to a car body width, so that the positions of the suspension members to be secured to the side frames are limited, eliminating flexibility of the positions to secure the suspension members.
As a sub-frame mounting structure, there is an example as shown in FIG. 10. FIG. 10 is a perspective view of the essential part of a conventional body work lower structure. A cross member 102 is mounted between side members 101 (the drawing shows only one, and the other one is omitted) and a sub-frame (not shown) is secured to the cross member 102. The side member 101 and the cross member 102 have a floor panel 103 fixed thereto to form a rectangular cross section.
Meanwhile, a great load of wheels is applied to the sub-frame through the suspensions. This requires to enhance rigidity of the sub-frame mounting sections and the joint section of the side member 101 and the cross member 102.